1. Field of the Invention
This invention relates to laser dyes, particularly to heterocyclic dyes containing hetero nitrogen and oxygen atoms, and more particularly to coumarin derivatives.
2. Description of the Prior Art
In the search for laser dyes operating at the blue-green transmission window of sea water, many substituted coumarins have been examined. Many such compounds have been reported to lase, as reported, for example by G. A. Reynolds and K. H. Drexhage in Optics Communications, Vol. 13, No. 3, p. 222, March 1975; P. R. Hammond and R. L. Atkins in J. Hetero. Chem., Vol. 12, p. 1061, October 1975; and P. R. Hammond in U.S. patent application Ser. No. 526,760, filed Nov. 25, 1974.
Two problems associated with liquid laser dye solutions, well known to those skilled in the art, are photochemical stability under flash and continuous wave excitation and efficiency of laser output power compared to electrical input into the flash lamp.